The part with having multiple libraries that do the same thing is always an interesting engineering case. Usually it's the case that different libraries support different features, so trying to settle on only one library is folly. Same thing when converting all of the existing zip code to handle a new library, who knows what will break, and even though it may be required production/management rarely want to take the time to make the switch.

Case in point I've been at multiple places that have had multiple JSON and XML libraries in the same product at the same time.